In a dynamic random access memory (DRAM), a plurality of memory cells are formed in a matrix manner on a substrate. Each memory cell in a DRAM device is constructed by at least one transistor and at least one storage capacitor. Commonly, either trench capacitor or stacked cells are used. The trenched structure is advantageous to the stacked structure in situations where the surface flatness of the device is of great importance. While trench capacitors are mostly used as storage capacitors in DRAMS, such structures are also used in some integrated circuits as general use capacitors, for example for decoupling purposes.
In DRAMs, as well as in other integrated circuits, it is desirable that a semiconductor chip hold as many circuits or memory cells as possible per unit area. The continuing trend to increase circuit density requires that DRAM cells occupy smaller and smaller areas over the long term. However, the inability to shrink cell voltages and currents as rapidly as the cell area means that proportionally more capacitance is demanded from the storage capacitor per unit of area defined by the initial etch of the trench at critical dimension. Thus, a need exists for a method of forming a trench storage capacitor having enhanced capacitance.